"Customary" means that a certain behavior, saying, or custom is widely accepted because of a long-standing practice and has become a norm generally followed by the general public. This kind of agreement is usually formed by people's mutual identification and interaction.
For example, a common example is that during a wedding ceremony, the groom must wear a ring for the bride to wear. This behavior has become a tradition and has become a custom in many cultures. Due to long-standing conventions, there are examples of conventions at weddings where the bride wears a white dress, and the groom keeps wedding preparations secret before the ceremony.
Another example is that in many countries and cultures, people exchange gifts with each other during the holidays. This behavior has become a social custom, and on special occasions such as Christmas, birthdays, wedding anniversaries, etc., people conventionally exchange gifts.
In short, an act, saying, or custom can be said to have been "conventional" when it is widely accepted because of a long-standing practice.
For example:1In this place, it is customary for everyone to exercise together every night.
2.This custom has become a common practice, and everyone must shake hands with each other when they meet.
3.In order to facilitate communication, they conventionally use sign language to communicate.
4.In this neighborhood, residents have agreed to clean the common areas together on a weekly basis.
5.In their culture, eating with chopsticks is already a convention.
6.In this department, it has become customary to take a group lunch break during working hours.
7.It is customary for the inhabitants of this place to do an hour of morning exercise every morning.
8.In this family, holiday dinners have become customary.
9.In this city, it has become customary not to spit.
10.In order to protect the environment, it is customary to reduce the use of plastic bags as much as possible.
11.This social event has been established and participants are expected to behave according to the prescribed etiquette.
12.In this team, it is customary to help each other.
13.In this culture, red is conventionally the auspicious color.
14.It is customary for the inhabitants of this place to exercise early every morning.
15.In this country, it is customary to commemorate the war dead.
16.In this family, the annual event of family reunion has become customary.
17.At this party, everyone agreed to play a game of catching monkeys.
18.In this village, the cultivation of rice has become a customary staple crop.
19.The festival has been conventionally celebrated as a national holiday.
20.In this country, the ceremony of raising and lowering the national flag has become a customary daily ritual.